<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>灯泡开关</title>
		<style type="text/css">
			div#box{
				text-align: center;
			}
			div#box div#btn{
				margin: auto;
				width: 50px;
				height: 50px;
				line-height: 50px;
				background: #ddd;
				border-radius: 50%;
				color: #fff;
				cursor: pointer;
			}
		</style>
	</head>
	<body>
		<div id="box">
			<div id="btn">开</div>
			<img id="img" src="img/pic_bulboff.gif" alt="" />
		</div>
		
		<script type="text/javascript">
			(function(){
				var btn = document.querySelector("#btn");
				var img = document.querySelector("#img");
				btn.onclick = function() {
					console.log("this:",this);
                    //console.log("this:",innerHTML);
                    if(this.innerHTML == "开") {
	                    img.src = "img/pic_bulbon.gif";
	                    this.innerHTML = "关";
	                    this.style.backgroundColor="green";
                    } else{
                    	img.src ="img/pic_bulboff.gif";
                    	this.innerHTML = "开";
                    	this.style.backgroundColor = "blue";
                    }
				}
			}());
		</script>
	</body>
</html>
